The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory captions and links exemplifying features within the Earth system. The community is invited to contribute digital imagery, short captions and relevant links.

Golden Mean in Sunflowers

This closeup of a sunflower is a good illustration of a mathematical formula found throughout Nature, known as the Golden Mean or Golden Ratio. The ratio is 1.6180339887499...(represented by the Greek letter phi), a proportional value found in seashells, like the nautilus, and in many flowering plants. The ancient Greeks used this formula in designing buildings like the Parthenon. In this photo, taken last summer in Smithville, Tennessee, the Golden Mean is expressed in the two intersecting rows of seeds that arc around the center of the flower, creating the striking pattern.